Box sealing device and packing machine

ABSTRACT

The present application provides a box sealing device, including two oppositely arranged rotating rods, and bending pieces convexly provided at one ends of the rotating rods; the two bending pieces are bent towards each other, and the bending pieces are arranged at an acute angle to the rotating rods. By means of rotating rods and bending pieces at an acute angle to the rotating rods, bending pieces bend two side covers, and allow hooking tongues of the side covers to hook each other to a certain extent, resulting in a simple structure and high stability.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation application of international application No. PCT/CN2020/076304, filed on Feb. 22, 2020, which claims the priority benefits of Chinese applications No. 201910132718.9, No. 201920234077.3, No. 201920234095.1 field on Feb. 22, 2019, Chinese applications No. 201910323145.8 and No. 201920557125.2 field on Apr. 22, 2019 and Chinese applications No. 201921832972.1 and No. 201921830360.9 field on Oct. 28, 2019, the contents of the above identified applications are hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present application relates to the field of packing machines, and in particular to a box sealing device, a packing machine and a side cover hooking method.

BACKGROUND OF THE PRESENT INVENTION

With the continuous deepening of industrial automation, manual work has been replaced by a large number of production line equipment. However, in the sealing link of a packing box, especially in sealing a packing box having side covers with hooking tongues, it substantially adopts manual operation since the hooking tongues of the two side covers need to be hooked together and the hooking tongues on the two sides need to be appropriately staggered to be hooked. Using manual work to complete the hooking operation hinders production automation. At present, the equipment instead of manual work is very difficult in automation and complex in apparatus structure, and cannot guarantee the success rate.

SUMMARY OF THE PRESENT INVENTION

The objection of the present application is to provide a box sealing device, comprising two oppositely arranged rotating rods, and bending pieces convexly provided at one ends of the rotating rods; the two bending pieces are bent towards each other, and the bending pieces are arranged at an acute angle to the rotating rods.

Preferably, the bending pieces comprise fixing parts attached to the rotating rods, and bending parts convexly arranged on the fixing parts.

Preferably, the acute angle between the bending part and the fixing part is 60-85 degrees.

Preferably, the bending pieces comprise bending piece bodies connected with the rotating rods, the bending parts are arranged at one ends of the bending piece bodies that away from the rotating rods; the two bending parts are arranged in a mutually staggered manner.

Preferably, the rotating rods are further provided with first protrusion pieces, and the two first protrusion pieces are oppositely arranged to limit a minimum distance between the two rotating rods.

Preferably, the box sealing device further comprises a mounting bracket, the rotating rods are hinged to two sides of the mounting bracket; the rotating rods are connected with a first driving member to drive the two rotating rods to move towards each other.

Preferably, the two rotating rods are respectively provided with a second protrusion piece, wherein one of the second protrusion pieces is provided on one of the rotating rods and protrudes towards the other rotating rod, and protruding heights of the second protrusion pieces are less than protruding heights of the bending pieces.

Preferably, the rotating rods are provided with first guide rails; the bending pieces are capable of moving along the first guide rails to be close to or away from the second protrusion pieces.

Preferably, the box sealing device further comprises a hooking mechanism, the hooking mechanism comprises a second driving member and a rotating plate, the second driving member is detachably connected with the mounting bracket, the rotating plate is fixed to the second driving member to rotate with the second driving member, and the two rotating rods are located on two sides of the rotating plate.

Preferably, the box sealing device further comprises extension parts, one ends of the bending piece bodies are connected with the rotating rods, the other ends of the bending piece bodies are connected with the extension parts, and the extension parts of the two bending pieces are arranged in a staggered manner.

Preferably, the extension parts are inclined relative to the bending piece bodies in a direction close to the rotating plate.

Preferably, pressing pieces are arranged at one ends of the bending piece bodies, the pressing pieces are positioned on one sides of the extension parts, the extension part and the pressing piece on one of the rotating rod are staggered with the extension part and the pressing piece on the other rotating rod.

Compared with the prior art, the application has the following advantages:

by means of rotating rods and bending pieces at an acute angle to the rotating rods, bending pieces bend two side covers, and allow hooking tongues of the side covers to hook each other to a certain extent, resulting in a simple structure and high stability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structure diagram of a packing box according to an embodiment;

FIG. 2 is a structure diagram of a box sealing device according to an embodiment of the present application;

FIG. 3 is a partially enlarged view of a portion A of FIG. 2;

FIG. 4 is a structure diagram of a box sealing device according to an embodiment of the present application;

FIG. 5 is a partially enlarged view of a portion B of FIG. 4;

FIG. 6 is a structure diagram of a box sealing device according to an embodiment of the present application;

FIG. 7 is a partially enlarged view of a portion C of FIG. 6;

FIG. 8 is a structure diagram of a box sealing device according to an embodiment of the present application;

FIG. 9 is a partially enlarged view of a portion D of FIG. 8;

in which: 101 packing box, 1011 side cover, 1012 main cover, 1013 side plate, 1014 main plate, 1015 box opening, 1016 hooking tongue, 1 box sealing device, 11 rotating rod, 1011 rotating part, 1102 rod part, 111 mounting bracket, 112 first driving member, 113 first protrusion piece, 114 second protrusion piece, 115 first guide rail, 116 mounting frame, 117 main frame, 118 third driving member, 119 second guide rail, 12 bending piece, 121 fixing part, 122 bending part, 123 bending piece body, 124 extension part, 125 pressing piece, 13 hooking mechanism, 131 second driving member, 132 rotating plate.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The following is a detailed description for the technical solutions of the present application in combination with specific implementations. However, it should be understood that, without further recitation, elements, structures and features in one implementation may be beneficially incorporated into other implementations.

In the description of the present application, it is to be understood that terms “first”, “second” are merely used for descriptive purpose and should not be interpreted to indicate or imply the relative importance or implicitly indicate the number of technical features indicated. Thus, the features defined by “first” and “second” may explicitly or implicitly include one or more of the features.

In the description of the present application, it is to be noted that the direction or positional relationships indicated by terms “upper”, “lower”, “bottom”, “inner” and the like are based on the positional relationships in the drawings, these terms are merely used to facilitate the description of the present application and simplify the description, yet do not indicate or imply that the devices or elements referred must have a particular orientation, be constructed and operated in particular orientation, and therefore should not be interpreted as a limitation on this application.

In the description of the present application, it is to be noted that, unless clearly indicates otherwise, terms “connect”, “connection” shall be generally understood, such as, may be fixed connection, detachable connection or integrated connection, may be directly connected, or indirectly connected through intermediate media, or inner communication of two components. For the person skilled in the art, the specific meanings of the above terms in the present application may be interpreted according to specific circumstance.

The implementations are only description for the preferred embodiments of the present application, not a limitation on the scope of the present application, without departing from the design spirit of the present application, all kinds of transformation and modification made by the person skilled in the art to the technical solution of the present application should fall within the protection scope defined by claims of the present application.

FIG. 1 shows a packing box 101, wherein two opposite side covers 1011 and two main covers 1012 located between the side covers 1011 are provided at one end of the packing box 101, the side covers 1011 of the packing box are connected with two opposite side plates 1013, the main covers 1012 of the packing box are connected with two opposite main plates 1014, and a box opening 1015 of the packing box after being unfolded is generally rectangular. The specific structures of the side covers 1011 are different according to different packing requirements, and as shown in FIG. 1, hooking tongues 1016 are provided on the side covers 1011. In a process of sealing the packing box, the packing box needs to be unfolded, and after a material to be packed is placed in, the side covers 1011 are bent, then the hooking tongues 1016 are hooked to each other, and the main covers 1012 are sealed.

With reference to FIGS. 2 and 3, a first embodiment of the present application provides a box sealing device 1 comprising a cover bending assembly comprising two oppositely arranged rotating rods 11, and bending pieces 12 convexly provided at one ends of the rotating rods 11; the two bending pieces 12 are bent towards each other, and the bending pieces 12 are arranged at an acute angle to the rotating rods 11.

According to the box sealing device 1 provided in the present embodiment, when the two rotating rods 11 drive the side covers 1011 to rotate to a preset position, the two bending pieces 12 bend the two side covers 1011 and make them form a certain obtuse angle to allow the hooking tongues 1016 of the side covers to hook each other to a certain extent, then the two main covers 1012 are pressed, and the two side covers 1011 are hooked completely, so that the box sealing device 1 is simple in structure and high in stability.

Specifically, the bending pieces 12 comprise fixing parts 121 attached to the rotating rods 11, and bending part 122 convexly arranged on the fixing parts 121. The bending piece 12 is disposed at an acute angle to the rotating rod 11 so that an acute angle is formed between the bending part 122 and the rotating rod 11, and a certain acute angle is formed between the fixing part 121 and the bending part 122. Preferably, the fixing parts 121 are detachably connected to the rotating rods 11. The bending pieces 12 can be manufactured in various specifications and sizes, and during use, the bending pieces 12 can be replaced according to the size or model of the packing box to be adapted to different models of packing boxes.

Preferably, the acute angle between the bending part 122 and the fixing part 121 is 60-85 degrees. The angle between the bending part 122 and the fixing part 121 can be adjusted according to the shape or size of the side cover. Taking the packing box having the side covers with hooking tongues as shown in FIG. 1 as an example, when the two side covers form an obtuse angle of about 160 degrees, the hooking of the hooking tongues of the two side covers would be very stable, and when the two main covers are closed in the next step, the two side covers are completely hooked.

As a preferred embodiment, as shown in FIGS. 4 and 5, the bending pieces 12 comprise bending piece bodies 123 connected with the rotating rods 11, the bending parts 122 are arranged at one ends of the bending piece bodies 123 that away from the rotating rods 11; the two bending parts 122 are arranged in a mutually staggered manner, and the two bending parts 122 do not interfere with each other during movement, so that the side covers 1011 can be bent to the preset position. Specifically, the bending piece bodies 123 are connected with the rotating rods 11 through the fixing parts 121, that is, the bending piece bodies 123 connect the fixing parts 121 and the bending parts 122. Here, the bending parts 122 are provided at one ends of the bending piece bodies 123, and when the two rotating rods 11 move toward each other, the two bending parts 122 bend the side covers 1011, and the two bending parts 122 do not collide with each other due to staggered arrangement, so that the side covers 1011 can be bent as much as possible. The bending piece bodies 123 are formed at a substantially right angle to the rotating rods 11, and after the side covers 1011 are bent, the bending piece bodies 123 are substantially fit with the side covers 1011, so that deformation of the side covers 1011 can be prevented. An acute angle is formed between the bending part 122 and the fixing part 121, thus, an obtuse angle is formed between the bending part 122 and the bending piece body 123; and after the two rotating rods 11 are moved to a preset position, an included angle is formed between the two bending parts 122, so that the two side covers 1011 are also arranged at a certain included angle, and the two side covers 1011 are hooked to each other to a certain extent accordingly.

The two rotating rods 11 can be moved toward or away from each other by rotating in a process of bending the side covers. In particular, as shown in FIG. 4, the box sealing device 1 further comprises a mounting bracket 111, the rotating rods 11 are hinged to two sides of the mounting bracket 111, the rotating rods 11 are connected with a first driving member 112 to drive the two rotating rods 11 to move towards each other. One end of the first driving member 112 is connected with the rotating rods 11 to drive the rotating rods 11 to be close to or away from each other, the first driving member 112 is rotatably connected with one ends of the rotating rods 11 that away from the bending pieces 12, and the other end of the first driving member 112 is connected with the mounting bracket 111. The lengths of the rotating rods 11 may be set as desired. It should be noted herein that the rotating rod 11 may be made of a lightweight material or be hollow to reduce the weight. The first driving member 112 selects a clamping cylinder, which is low in weight and cost and long in service life, and can also be other driving forms, such as an electric cylinder or a hydraulic cylinder, and can be selected according to requirements.

Optionally, the two rotating rods 11 are arranged symmetrically, and the two rotating rods 11 are coordinated to move synchronously so as to be suitable for the packing box with the same two side covers, ensuring simultaneous bending and hooking of the two side covers.

As a preferred embodiment, as shown in FIG. 5, the rotating rods 11 are further provided with first protrusion pieces 113, and the two first protrusion pieces 113 are oppositely arranged to limit a minimum distance between the two rotating rods 11, so that a situation that the side covers 1011 cannot be inserted due to the incapability of effectively applying force to the two side covers 1011 since the distance between the two rotating rods 11 is too small and contact positions of the rotating rods 11 and the side covers 1011 are too close to the edges of the side covers 1011 can be prevented. Here, the first protrusion pieces 113 are bolts provided on the rotating rods 11, and the minimum distance between the two rotating rods 11 can be adjusted by adjusting the heights of the bolts protruding from the rotating rods 11, thereby being adapted to the bending and insertion requirements of the side covers 1011 of different sizes. The number of the first protrusion pieces 113 may be set to two, that is, one on each of the two rotating rods 11, and the two first protrusion pieces 113 are oppositely arranged. Specifically, each of the rotating rods 11 comprises: a rotating part 1101 rotatably connected with the mounting bracket 111, and a rod part 1102 connected with the rotating part 1101. The rod part 1102 is detachably connected with the rotating part 1101, and the first protrusion piece 113 is arranged on the rotating part 1101. Therefore, when bending the side covers of different specifications, it is not necessary to disassemble the entire rotating rods, but only to replace the rod parts. The first protrusion pieces 113 are located on the rotating parts 1101, and the first protrusion pieces 113 protrude to middle of the two rotating rods 11.

In order to further improve the success rate of hooking, as a preferred embodiment, as shown in FIGS. 4 and 5, the two rotating rods 11 are respectively provided with a second protrusion piece 114, wherein one of the second protrusion pieces 114 is provided on one of the rotating rods 11 and protrudes towards the other rotating rod 11, and protruding heights of the second protrusion pieces 114 are less than protruding heights of the bending pieces 12, that is, the second protrusion pieces 114 are connected with one ends of the rotating rods 11 that away from the first driving member 112 and protrude to the middle of the two rotating rods 11. By the cooperation of the second protrusion pieces 114 and the bending pieces 12, when the two rotating rods 11 move towards each other, when the bending pieces 12 bend the side covers 1011 to the preset position, the second protrusion pieces 114 come into contact with a box body and press the box body to deform, and the slightly deformed box body makes the hooking of the side covers simpler, and the box sealing device of the present embodiment is used for the bending and hooking of the side covers, and is simple in structure and high in success rate.

Preferably, as shown in FIG. 5, the rotating rods 11 are provided with first guide rails 115; the bending pieces 12 are capable of moving along the first guide rails 115 to be close to or away from the second protrusion pieces 114. Since the distance between the optimum positions of the different side covers 1011 to bear applied force and the stressed position of the box body are different, the distance between the bending piece 12 and the second protrusion piece 114 can be adjusted to meet the requirements of the packing box of the different size or shapes for bending the side covers. Preferably, the first guide rails 115 are sliding groove formed in the rotating rods 11, the bending pieces 12 are clamped in the sliding grooves so as to move along the sliding grooves, and when moving to preset positions, the bending pieces 12 and the rotating rods 11 can be fixed to each other by means of bolts or snaps, etc. It should be noted herein that the first guide rails 115 are not limited to the above-mentioned structure, and the guide rails may adopt structures such as a slide bar or a slideway protruding from the rotating rod 11 and then be positioned in cooperation with the bolts or the snaps. For example, the bending pieces 12 are connected with the rotating rods 11 by means of slidable snaps, so that an effective adjustment of the distance between each bending piece 12 and the corresponding second protrusion piece 114 can be achieved.

In order to improve the success rate of hooking, as shown in FIG. 6, as a preferred embodiment, the box sealing device 1 further comprises a hooking mechanism 13 provided between the two rotating rods 11, wherein the hooking mechanism 13 comprises a second driving member 131 and a rotating plate 132, the second driving member 131 is detachably connected with the mounting bracket 111, the rotating plate 132 is fixed to the second driving member 131 to rotate with the second driving member 131, and the two rotating rods 11 are located on two sides of the rotating plate 132. The second driving member 131 in this embodiment selects a rotating cylinder. According to the box sealing device 1, by means of the hooking mechanism 13, while the side covers 1011 are bent, the rotating plate 132 is inserted between the two side covers 1011, and the second driving member 131 drives the rotating plate 132 to rotate 180°, the hooking of the side covers 1011 is realized and the hooking tongues 1016 of the side covers 1011 are completely hooked, the device is simple in structure and has a high success rate of complete hooking of the side covers 1011.

Preferably, as shown in FIG. 7, the bending pieces 12 further comprise extension parts 124, one ends of the bending piece bodies 123 are connected with the rotating rods 11, the other ends of the bending piece bodies 123 are connected with the extension parts 124, and the extension parts 124 of the two bending pieces 12 are arranged in a staggered manner. One ends of the bending piece bodies 123 are connected with the rotating rods 11 via the fixing parts 121, the other ends of the bending piece bodies 123 are connected with the extension parts 124 via the bending parts 122, that is, the extension parts 124 are provided at the ends of the bending parts 122, the extension parts 124 as extension of the bending parts 122 are arranged in a mutually staggered manner. The extension parts 124 are inclined relative to the bending piece bodies 123 in a direction close to the rotating plate 132, so that a certain included angle can be formed between the two extension parts 124 after the two rotating rods 11 reach the preset position, and an included angle can also be formed between the side covers 1011 in contact with the extension parts 124 to facilitate the subsequent hooking of the side covers 1011. The two extension parts 124 are arranged in a staggered manner so that the two extension parts 124 do not interfere with each other during operation and the side covers 1011 can be bent to the preset position. In the present embodiment, the rotating rods 11 may also be provided with the first guide rails 115 such that the bending pieces 12 may move along the first guide rails 115 to be close to or away from the mounting bracket 111, and the bending pieces 12 may be positioned at preset positions on the rotating rods 11 to be adapted to the bending and hooking of side covers 1011 of different specifications. In the present embodiment, the first guide rails 115 select sliding grooves, the bending pieces 12 are provided with sliding blocks matched with the sliding grooves, and can be fixed by means of bolts or the like when moving to preset positions.

As shown in FIGS. 8 and 9, as a preferred embodiment of the embodiments mentioned above, pressing pieces 125 are arranged at one ends of the bending piece bodies 123, the pressing pieces 125 are positioned on one sides of the extension parts 124, the extension part 124 and the pressing piece 125 on one of the rotating rod 11 are staggered with the extension part 124 and the pressing piece 125 on the other rotating rod 11. The pressing piece 125 and the extension part 124 are both provided at the ends of the bending piece bodies 123 and arranged side by side. Due to the staggered arrangement of the extension parts 124, the pressing pieces 125 are arranged in a staggered manner, and the bending pieces 12 do not interfere with each other when moving toward each other. That is, the extension part 124 of one of the rotating rods 11 is arranged opposite to the pressing piece 125 of the other rotating rod 11. The first driving member 112 drives the two rotating rods 11 to move towards each other, and at the same time, drives the bending pieces 12 to be close to each other, and the bending pieces 12 further come into contact with the box body; when the extension parts 124 bend the side covers 1011, one of the pressing pieces 125 presses down the side cover 1011 on one side, and at the same time, the other pressing piece 125 is inserted into the edge of the side cover 1011 on the other side, thereby further improving the success rate of hooking the two side covers 1011 and achieving the hooking of the side covers 1011.

When the box sealing device 1 according to the first embodiment of the present application is applied as a part of a packing machine to the packing of materials, it is usually necessary to mount the box sealing device 1 to the packing machine. Thus, as shown in FIGS. 2, 4, 6 and 8, the box sealing device 1 further comprises: a mounting frame 116 connected with the mounting bracket 111, and a third driving member 118 connected with the mounting frame 116, wherein the third driving member 118 is mounted on a main frame 117, and the third driving member 118 can drive the mounting frame 116 to move. In order to stabilize the movement of the box sealing device 1, a second guide rail 119 may be provided on the main frame 117, and the rotating rod 11 may move along the second guide rail 119 under the driving of the third driving member 118. The third driving member 118 selects an electrical cylinder for more accurate adjustment. The third driving member 118 may drive the rotating rod 11 to move close to the packing box 101. Specifically, the third driving member 118 may select an electric cylinder, or any other driving member capable of driving the sectioned positioning movement of the cover bending assembly. The third driving member 118 drives the rotating rods 11 to move towards the packing box 101 stage by stage, so that the box sealing device 1 can bend the side covers 101 stage by stage to be adapted to the requirements of packing boxes 101 of different sizes for bending and hooking the side covers 101.

The box sealing device provided in the first embodiment of the present application is simple in structure and easy to mount, and, when being used for product packing, can be used in combination with an device used in working processes such as box blank unfolding, packing box grabbing and material grabbing, and can also be used in combination with assemblies used in other packing processes of main covers or side covers.

The second embodiment of the present application further provides a packing machine comprising the box sealing device 1 described above.

The third embodiment of the present application further provides a method for hooking side covers, comprising the following steps:

driving, by a first driving member 112, two rotating rods 11 to move towards each other to drive bending pieces 12 fixed to the rotating rods 11 to move towards each other;

allowing bending parts 15 of the two bending pieces 12 to be close to each other, to come into contact with a packing box and to bend side covers 1011 of the packing box;

inserting rotating plate 132 of a hooking mechanism 13 between the bent side covers 1011;

driving, by a second driving member 131, the rotating plate 132 to rotate once by 180° so that the side covers 1011 are completely hooked;

and driving, by a third driving member 118, the box sealing device 1 to be away from the packing box 101.

The above-mentioned method achieves the hooking of the side covers with the hooking tongues, the structure is simple and the success rate of hooking the side covers 1011 is high.

As a preferred embodiment, the method comprises the following steps:

driving, by a third driving member 118, a box sealing device 1 to a designated position;

driving, by a first driving member 112, two rotating rods 11 to move towards each other to drive bending pieces 12 fixed to the rotating rods 11 to move towards each other;

allowing bending parts 15 of the two bending pieces 12 to be close to each other, to come into contact with a packing box and to bend side covers 1011 of the packing box;

allowing pressing pieces 125 to press down the side cover 1011 on one side and to be inserted into the edge of the side cover 1011 on the other side, so that the side covers 1011 are preliminarily hooked; inserting rotating plate 132 of a hooking mechanism 13 between the bent side covers 1011;

driving, by a second driving member 131, the rotating plate 132 to rotate once by 180° so that the side covers 1011 are completely hooked; and

driving, by the third driving member 118, the box sealing device 1 to be disengaged from the packing box.

In the above-mentioned method, the pressing pieces and the rotating plate act on the side covers step by step to achieve twice hooking of the side covers, so that the success rate of hooking the side covers is greatly improved. 

1. A box sealing device, comprising two oppositely arranged rotating rods, and bending pieces convexly provided at one ends of the rotating rods; the two bending pieces are bent towards each other, and the bending pieces are arranged at an acute angle to the rotating rods.
 2. The box sealing device of claim 1, wherein the bending pieces comprise fixing parts attached to the rotating rods, and bending parts convexly arranged on the fixing parts.
 3. The box sealing device of claim 2, wherein the acute angle between the bending part and the fixing part is 60-85 degrees.
 4. The box sealing device of claim 2, wherein the bending pieces comprise bending piece bodies connected with the rotating rods, the bending parts are arranged at one ends of the bending piece bodies that away from the rotating rods; the two bending parts are arranged in a mutually staggered manner.
 5. The box sealing device of claim 4, wherein the rotating rods are further provided with first protrusion pieces, and the two first protrusion pieces are oppositely arranged to limit a minimum distance between the two rotating rods.
 6. The box sealing device of claim 4, further comprising a mounting bracket, the rotating rods are hinged to two sides of the mounting bracket; the rotating rods are connected with a first driving member to drive the two rotating rods to move towards each other.
 7. The box sealing device of claim 4, wherein the two rotating rods are respectively provided with a second protrusion piece, wherein one of the second protrusion pieces is provided on one of the rotating rods and protrudes towards the other rotating rod, and protruding heights of the second protrusion pieces are less than protruding heights of the bending pieces.
 8. The box sealing device of claim 7, wherein the rotating rods are provided with first guide rails; the bending pieces are capable of moving along the first guide rails to be close to or away from the second protrusion pieces.
 9. The box sealing device of claim 6, further comprising a hooking mechanism, the hooking mechanism comprises a second driving member and a rotating plate, the second driving member is detachably connected with the mounting bracket, the rotating plate is fixed to the second driving member to rotate with the second driving member, and the two rotating rods are located on two sides of the rotating plate.
 10. The box sealing device of claim 9, further comprising extension parts, one ends of the bending piece bodies are connected with the rotating rods, the other ends of the bending piece bodies are connected with the extension parts, and the extension parts of the two bending pieces are arranged in a staggered manner.
 11. The box sealing device of claim 10, wherein the extension parts are inclined relative to the bending piece bodies in a direction close to the rotating plate.
 12. The box sealing device of claim 10, wherein pressing pieces are arranged at one ends of the bending piece bodies, the pressing pieces are positioned on one sides of the extension parts, the extension part and the pressing piece on one of the rotating rod are staggered with the extension part and the pressing piece on the other rotating rod.
 13. A packing machine, comprising the box sealing device in claim
 9. 14. A packing machine, comprising the box sealing device in claim
 12. 15. A method for hooking side covers, adopting the packing machine in claim 13, comprising the following steps: driving, by a first driving member, two rotating rods to move towards each other to drive bending pieces fixed to the rotating rods to move towards each other; allowing bending parts of the two bending pieces to be close to each other, to come into contact with a packing box and to bend side covers of the packing box; inserting rotating plate of a hooking mechanism between the bent side covers; driving, by a second driving member, the rotating plate to rotate once by 180° so that the side covers are completely hooked; and driving, by a third driving member, the box sealing device to be away from the packing box.
 16. A method for hooking side covers, adopting the packing machine in claim 14, comprising the following steps: driving, by a third driving member, a box sealing device to a designated position; driving, by a first driving member, two rotating rods to move towards each other to drive bending pieces fixed to the rotating rods to move towards each other; allowing bending parts of the two bending pieces to be close to each other, to come into contact with a packing box and to bend side covers of the packing box; allowing pressing pieces to press down the side cover on one side and to be inserted into the edge of the side cover on the other side, so that the side covers are preliminarily hooked; inserting rotating plate of a hooking mechanism between the bent side covers; driving, by a second driving member, the rotating plate to rotate once by 180° so that the side covers are completely hooked; and driving, by the third driving member, the box sealing device to be disengaged from the packing box. 